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Abstract Background Evolutionary divergence and genetic variation are often linked to differences in microbial community structure and diversity. While environmental factors and diet heavily influence gut microbial communities, host species contributions are harder to quantify. Closely related species living in sympatry provide a unique opportunity to investigate species differences without the confounding effects of habitat and dietary variation. We therefore compared and contrasted the gut microbiota of three sympatric plover species: the widespread Kittlitz’s and white-fronted plovers (Anarhynchus pecuarius and A. marginatus) and the endemic and vulnerable Madagascar plover (A. thoracicus). Results We found no significant differences in the beta diversity (composition) of the gut microbiota of the three species. However, A. thoracicus exhibited higher intraspecific compositional similarity (i.e. lower pairwise distances) than the other two species; this pattern was especially pronounced among juveniles. By contrast, microbial alpha diversity varied significantly among the species, being highest in A. pecuarius, intermediate in A. marginatus and lowest in A. thoracicus. This pattern was again stronger among juveniles. Geographical distance did not significantly affect the composition of the gut microbiota, but genetic relatedness did. Conclusion While patterns of microbial diversity varied across species, the lack of compositional differences suggests that habitat and diet likely exert a strong influence on the gut microbiota of plovers. This may be enhanced by their precocial, ground-dwelling nature, which could facilitate the horizontal transmission of microbes from the environment. We hypothesise that gut microbiota diversity in plovers primarily reflects the ecological pool of microbiota, which is subsequently modified by host-specific factors including genetics. The reduced microbial and genetic diversity of the endemic A. thoracicus may hinder its ability to adapt to environmental changes, highlighting the need for increased conservation efforts for this vulnerable species.

Abstract In mammals, sexual size dimorphism often reflects the intensity of sexual selection, yet its connection to genomic evolution remains unexplored. Gene family size evolution can reflect shifts in the relative importance of different molecular functions. Here, we investigate the associate between brain development gene repertoire to sexual size dimorphism using 124 mammalian species. We reveal significant changes in gene family size associations with sexual size dimorphism. High levels of dimorphism correlate with an expansion of gene families enriched in olfactory sensory perception and a contraction of gene families associated with brain development functions, many of which exhibited particularly high expression in the human adult brain. These findings suggest a relationship between intense sexual selection and alterations in gene family size. These insights illustrate the complex interplay between sexual dimorphism, gene family size evolution, and their roles in mammalian brain development and function, offering a valuable understanding of mammalian genome evolution.

Abstract A combination of life history traits and environmental conditions has been highlighted as the main drivers of avian breeding success. While drivers of breeding success are well known in some species, especially birds in northern, temperate regions; species in other parts of the world have received relatively little attention. In this study, we used a long‐term dataset on breeding success of tropical plovers from south‐west Madagascar to investigate whether nest survival changed over time and whether the drivers of nest survival were similar for multiple species breeding in the same arid habitat. In the 12‐year period of 2009–2020, we monitored 2077 nests for three species with different breeding strategies: 1185 nests of Kittlitz's plovers (Anarhynchus pecuarius) with a flexible breeding strategy and uniparental care; and 565 nests of white‐fronted plovers (A. marginatus) and 327 nests of Madagascar plovers (A. thoracicus) which both have biparental care. We found that nest survival was associated with a combination of clutch‐size, age of nest and year among the three plover species. In addition, annual variation in climatic conditions associated with El Niño/La Niña events were included in the most supported survival models for Kittlitz's and white‐fronted plovers, but the effects were not significant. Overall estimates of daily nest survival were similar for all three species: Kittlitz's plover: 0.950 ± 0.002 SE, Madagascar plover: 0.919 ± 0.007 SE, and white‐fronted plover: 0.862 ± 0.047 SE. Estimates of nest success for the breeding season, based on increases in daily nest survival with the clutch age during the incubation periods (26 days for Kittlitz's plovers and 29 days for Madagascar and white‐fronted plovers), were relatively low: Kittlitz's plover: 0.161 ± 0.056 SE, Madagascar plover: 0.287 ± 0.022 SE, and white‐fronted plover: 0.228 ± 0.019 SE. All three species had a combination of factors affecting nest survival, both environmental and life history traits.

Agricultural intensification has affected wildlife across Europe, triggering steep declines and regional extinctions of farmland birds. Effective conservation activities are essential for the preservation of biodiversity in an agricultural landscape, but current efforts have not succeeded in halting these declines. Here we investigate a ground-nesting shorebird, the collared pratincole Glareola pratincola, which has shifted its habitat use in Central Europe over the last 20 years from alkaline grasslands to intensively managed agricultural fields. We show that nesting success was different between three agricultural habitat types, with the highest nesting success in fallow lands and the lowest in row crops. Nesting success was also associated with the timing of breeding and breeding density, as nests produced early in the breeding season and those in high-breeding-density areas hatched more successfully than those produced later in the season and at low density. We implemented direct conservation measures including marking nests and negotiating with farmers to avoid cultivating the field between nest markers, controlling nest predators and, most recently, creating suitable nesting sites and foraging areas for pratincoles. As a result of these conservation actions, nest survival increased from 11.2% to 83.5% and the size of the breeding population increased from 13 to 56 pairs during 2012–2021. Thus, we show that agricultural landscapes can continue to provide suitable habitats, and targeted conservation actions have the potential to reverse the declines of farmland species.

To execute environmental education effectively, the success and impacts of educational activities must be assessed. In areas of high biodiversity there is generally a lack of evaluation of the impact of environmental education. In this study we investigate the effect of a one-time classroom activity on student knowledge of local environmental issues, environmental attitudes and aspirations. The project was conducted on the island of Maio, Cabo Verde, a small, highly biodiverse island, as part of a classroom visit programme with the local environmental organization, Maio Biodiversity Foundation. We visited every fourth-grade class (i.e. students with an age range of 9–10 years) on the island (a total of 142 students) and delivered a half-day classroom activity. The results show that this activity did not influence environmental attitudes; however, it did significantly improve student knowledge and awareness of local environmental issues. This study shows that environmental education should not be assumed to improve attitudes and knowledge but requires individual evaluation for each type of activity. For environmental education to reach its full potential, activities should be planned in response to evaluation results.

Global biodiversity loss is a major environmental concern. The wildlife on islands are particularly vulnerable to threats posed by alien predators, habitat loss and overexploitation. Effective conservation management of vulnerable species requires reliable information on vital population rates for all life stages and an understanding of key environmental drivers. However, demographic data are often not available for island populations before they decline or are extirpated. Here, we use Cormack–Jolly–Seber (CJS) models and 15 years of data for 1370 juveniles and 687 adults to estimate apparent survival for a genetically distinct resident population of Kentish plovers Charadrius alexandrinus on the island of Maio, Cabo Verde. We report two main findings. First, environmental conditions have a large effect on demographic performance since chicks that hatch during dry years experience a tenfold reduction in first‐year survival compared to chicks that hatch during wet years. Second, female and male plovers in Maio are expected to live for 7.41 ± 0.69 (mean ± SE) years and 6.75 ± 0.64 years, respectively, due to relatively high annual survival among comparable‐sized shorebirds. High adult survival thus could buffer the population against low reproductive success that this population has experienced over the last decade. Cabo Verde is typical of tropical islands with increased development that can impact native breeders and/or will accelerate habitat loss. Thus, more frequent droughts associated with climate change may exacerbate the prospects of native wildlife on many islands.

Preen oil, the secretion from the uropygial gland of birds, may have a specific function in incubation. Consistent with this, during incubation, the chemical composition of preen oil is more likely to differ between sexes in species where only one sex incubates than in species where both sexes incubate. In this study, we tested the generality of this apparent difference, by investigating sex differences in the preen oil composition of a shorebird species, the Kentish plover (Anarhynchus, formerly Charadrius, alexandrinus). As both sexes incubate in this species, we predicted the absence of sex differences in preen oil composition during incubation. In the field, we sampled preen oil from nine females and 11 males during incubation, which we analysed with gas chromatography–mass spectrometry (GC–MS). Consistent with predictions, we found no sex difference in preen oil composition, neither in beta diversity (Bray-Curtis dissimilarities) nor in alpha diversity (Shannon index and number of substances). Based on these results, we cannot conclude whether preen oil has a function during incubation in Kentish plovers. Still, we discuss hypothetical roles, such as olfactory crypsis, protection against ectoparasites or olfactory intraspecific communication, which remain to be tested.

Abstract Social behaviour is thought to be a major component of survival, reproduction, and resilience of populations. Thus, it is a key component in management and conservation of wild populations. In polygynous breeding species, group size influences the reproductive success of males and females, and hence it is essential to understand the environmental and demographic factors that shape the phenology of group size within populations. Here, we investigate harem size and its determinants using a 15‐year dataset of annual harem size phenology‐based metrics from a reintroduced population of wild Przewalski horses in Hortobágy National Park, Hungary. From the initial reintroduction of 21 animals in 1997, the population grew to 174 animals in 2012. During that same period, the number of harems increased from three to 23. Despite the 8‐fold increase in population size, harem sizes remained stable, and variability among harems within years decreased. The annual phenological cycle of harem size was not consistent over the 15‐year period, and the associated annual phenology‐based metrics varied differently over the years. The best predictors of our phenology‐based harem size metrics were adult sex ratio, annual adult mortality and annual mean number of harems, with some evidence that mean age of harem stallions and drought severity were contributing factors. Our findings reveal that complex interactions between demography, climate, and harem size can emerge in social animals. Taken together, our results demonstrate that intrinsic population processes can regulate group size even in the presence of non‐stationary climatic conditions during periods of growth in human‐introduced, semi‐free ranging animal populations.

Abstract TP53 aberrations predict chemoresistance and represent a contraindication for the use of standard chemoimmunotherapy in chronic lymphocytic leukaemia (CLL). Recent next‐generation sequencing (NGS)‐based studies have identified frequent low‐burden TP53 mutations with variant allele frequencies below 10%, but the clinical impact of these low‐burden TP53 mutations is still a matter of debate. In this study, we aimed to scrutinise the subclonal architecture and clinical impact of TP53 mutations using a sensitive, NGS‐based mutation analysis in a ‘real‐world’ cohort of 901 patients with CLL. In total, 225 TP53 mutations were identified in 17.5% (158/901) of the patients; 48% of these alterations represented high‐burden mutations, while 52% were low‐burden TP53 mutations. Low‐burden mutations as sole alterations were identified in 39% (62/158) of all mutated cases with 82% (51/62) of these being represented by a single low‐burden TP53 mutation. Patients harbouring low‐burden TP53 mutations had significantly lower time to first treatment compared to patients with wild‐type TP53. Our study has expanded the knowledge on the frequency, clonal architecture, and clinical impact of low‐burden TP53 mutations. By demonstrating that patients with sole low‐burden TP53 variants represent more than one‐third of patients with TP53 mutations and have an increased risk for treatment initiation, our findings strengthen the need to redefine the threshold of TP53 variant reporting to below 10% in the routine diagnostic setting.

For species without parental care, such as sea turtles, nest site selection is particularly important for embryo development, hatchling survival and, ultimately, reproductive success. We conducted an 8-year (2012–2019) capture–mark–recapture study of the re-nesting behaviour of loggerhead turtles Caretta caretta to identify both inter- and intra-beach patterns of nest site selection. Our study site, Maio Island in the archipelago of Cabo Verde, hosts one of the largest loggerhead turtle nesting colonies globally. Of 1,060 females analysed, 77% laid repeated clutches within 15 km of their previous nesting sites both between and within nesting seasons. This site fidelity was particularly high (64–71%) for turtles nesting on the east coast of Maio Island. In two areas of the island (north-west and south-east) individual nesting zone consistency was extremely low (10–25%). In all cases extra-zone re-nesting events mainly occurred on the east coast. We also found that females avoided re-nesting near the shoreline, which is particularly relevant in the context of rising sea levels. Overall, loggerhead turtles nesting in Maio Island are philopatric but are using a bet-edging strategy to distribute nests amongst several beaches, choosing the safest area within each beach to maximize their reproductive success. This study highlights the priority sites for protection on Maio Island and could help to optimize capture–mark–recapture programmes. The data reveal the potential for adaptive responses to projected sea level rises.

A detailed Review across animal and human societies provides insight on the causes and consequences of adult sex ratio skew.

Abstract Complex parenting has been proposed to contribute to the evolutionary success of vertebrates. However, the evolutionary routes to complex parenting and the role of parenting in vertebrate diversity are still contentious. Although basal vertebrates provide clues to complex reproduction, these are often understudied. Using 181 species that represent all major lineages of an early vertebrate group, the salamanders and newts (Caudata, salamanders henceforth) here we show that fertilisation mode is tied to parental care: male-only care occurs in external fertilisers, whereas female-only care exclusively occurs in internal fertilisers. Importantly, internal fertilisation opens the way to terrestrial reproduction, because fertilised females are able to deposit their eggs on land, and with maternal care provision, the eggs could potentially develop outside the aquatic environment. Taken together, our results of a semi-aquatic early vertebrate group propose that the diversity and follow-up radiation of terrestrial vertebrates are inherently associated with a complex social behaviour, parenting.

Tropical islands harbour a disproportionally high number of endemic species, which face increasing threats due to habitat loss, disturbance and introduced alien predators. Long-term demographic studies are needed to understand how such threats may impact on population productivity. We report an investigation of a key demographic parameter, nest survival, over a 13-year period in a small ground-nesting shorebird on the island of Maio (Cabo Verde). Similar to many tropical islands, Maio is expected to face increased tourism, disturbance, and potential loss of nesting habitats. We monitored over 700 nests of the largest, year-round resident breeding population of Kentish plover in the Atlantic Ocean archipelago. Our work produced three important findings. First, we show that nest survival differed among the major habitats of the main breeding site, the Salinas do Porto Inglês, because nests in the salt-extraction area had higher daily survival rates DSR = 0.9654 ± 0.0076 SE than nests in grasslands DSR = 0.9557 ± 0.0038 SE. The salt-extraction is a dynamic habitat that is naturally regulated by rainfall and sea water inflow and managed with traditional methods for salt-extraction. Kentish plovers breed on small islets surrounded by salty water where mammalian predators may have restricted access. Second, we found that breeding densities of plovers decreased from 0.11 nests/ha to 0.03 nests/ha over 13 years. Last, we show that nest survival declined from 0.9784 ± 0.0107 in 2007 to 0.8967 ± 0.0401 in 2019. We suggest that the declining breeding density and nest survival may be driven by a combination of ecological factors including predation by native and introduced species, and by increased human disturbance. To help maintain sustainable levels of nest survival and to ensure long-term persistence of this Kentish plover population, we propose to incorporate traditional Salinas management into direct conservation actions, to reduce human disturbance and manage nest predators to help nest survival on tropical islands.

Summary: Arctic environments are changing rapidly and if we are to understand the resilience of species to future changes, we need to investigate alterations in their life histories. Egg size and egg shape are key life-history traits, reflecting parental investment as well as influencing future reproductive success. Here we focus on egg characteristics in two Arctic shorebirds, the Dunlin (Calidris alpina) and the Temminck’s stint (Calidris temminckii). Using egg photos that encompass their full breeding ranges, we show that egg characteristics exhibit significant longitudinal variations, and the variation in the monogamous species (Dunlin) is significantly greater than the polygamous species (Temminck’s stint). Our finding is consistent with the recent “disperse-to-mate” hypothesis which asserts that polygamous species disperse further to find mates than monogamous species, and by doing so they create panmictic populations. Taken together, Arctic shorebirds offer excellent opportunities to understand evolutionary patterns in life history traits.

Understanding the main ecological factors of the nesting habitat of shorebirds is of great significance in relation to their protection and habitat management. Habitat loss and change due to a lack of water threaten the biodiversity of shorebirds, with impacts likely to be most pronounced in arid lands. We collected the data of 144 nesting sites and 10 ecological factors during the breeding season from April to July each year in 2019 and 2020 in nine river districts in Xinjiang. The MaxEnt model was applied to assess the suitability of nesting habitats for Kentish plovers (Charadrius alexandrinus) in the study area to examine the main factors affecting their nesting habitat. The most suitable nesting habitats are mostly distributed in plain reservoirs in the middle part of the Northern Slope of the Tianshan Mountains, Ebinur Lake and its eastern position in the southwestern Junggar Basin, near Ulungur Lake of the Ulungur river area and the southern Irtysh river area. The distance from water, normalized difference vegetation index, mean temperature of the breeding season, slope, and land use were the main factors affecting the nesting habitat selection of Kentish plovers. It was found that the proportion of suitable nesting habitat protected for the Kentish plovers in the study area was low (851.66 km2), accounting for only 11.02% of the total suitable nesting habitat area. In view of the scarcity and importance of water bodies in arid lands and the lack of protection for Kentish plovers at present, it is suggested to strengthen the conservation and management of the regional shorebirds and their habitats by regulating and optimizing the allocation of water resources.

Abstract Males and females often display different behaviours and, in the context of reproduction, these behaviours are labelled sex roles. The Darwin–Bateman paradigm argues that the root of these differences is anisogamy (i.e., differences in size and/or function of gametes between the sexes) that leads to biased sexual selection, and sex differences in parental care and body size. This evolutionary cascade, however, is contentious since some of the underpinning assumptions have been questioned. Here we investigate the relationships between anisogamy, sexual size dimorphism, sex difference in parental care and intensity of sexual selection using phylogenetic comparative analyses of 64 species from a wide range of animal taxa. The results question the first step of the Darwin–Bateman paradigm, as the extent of anisogamy does not appear to predict the intensity of sexual selection. The only significant predictor of sexual selection is the relative inputs of males and females into the care of offspring. We propose that ecological factors, life-history and demography have more substantial impacts on contemporary sex roles than the differences of gametic investments between the sexes.

Due to the influence of bio-geographical and environmental factors, as well as anthropogenic landscape features, organisms show different reproductive strategies among different populations. There is a lack of detailed information on the reproductive biology of Kentish plover Charadrius alexandrinus in arid lands in Central Asia. In this study, we summarized the characteristics of the reproductive biology of three geographically distinct plover populations in Aibi Lake in northwestern Xinjiang, Taitema Lake in southern Xinjiang and artificial reservoirs around Urumqi City in northern Xinjiang, based on 440 eggs from 158 nests observed and analyzed from April to July of 2019 and 2020. We found that there was no significant difference in clutch size among the three populations. However, the egg size of the Taitema Lake population was significantly larger than those of the other two populations, whilst the egg volume and clutch volume of the artificial reservoirs’ populations were significantly larger than that of Aibi Lake. With the postponement of laying dates, the northern and northwestern populations showed the characteristics of a small clutch size and a relatively small egg size, respectively, and a decrease in reproductive output. The heavier female plovers in Taitema Lake laid eggs earlier, and there was a significantly positive correlation between female body mass and clutch size and egg size. The tarsometatarsus length of the female plovers was significantly positively correlated with the reproductive output in all three populations. The model selection results show that female body size and ambient temperature restrict the egg size and reproductive output of Kentish plovers, which is consistent with the upper limit hypothesis of the maternal condition and maternal constraint. Our data support the hypothesis that Kentish plovers show distinct flexibility in their breeding strategies to cope with the harsh natural environment in the arid lands of Xinjiang, China. The results of a relatively high average clutch size and average egg size imply that the saline wetlands of Western China are important breeding habitats for Kentish plovers.

Abstract Whilst the immune system often varies seasonally and exhibits differences between males and females, the general patterns in seasonality and sex differences across taxa have remained controversial. Birds are excellent model organisms to assess these patterns, because the immune system of many species is well characterised. We conducted a meta-analysis using 41 wild bird species from 24 avian families to investigate sex differences and seasonal (breeding/non-breeding) variations in immune status, including white blood cell counts, phytohaemagglutinin (PHA) test, bacteria-killing ability (BKA), haemolysis and haemagglutination assays. We found male-biased macrophage concentration, BKA and haemolysis titers, but only during the breeding season. Sex-specific heterophil concentrations, heterophil/lymphocyte ratios and PHA responses differed between breeding and non-breeding, suggesting larger changes in males than in females. Importantly, sex differences in immune status are stronger during the breeding period than during the non-breeding period. Taken together, our study suggests that both seasonal variation and sex differences in immune system are common in birds, although their associations are more complex than previously thought.

Abstract Background The allocation of resources between offspring size and number is a central question of life-history theory. Although several studies have tested the existence of this trade-off, few studies have investigated how environmental variation influences the allocation of resources to offspring size and offspring number. Additionally, the relationship between population dynamics and the offspring size and number allocation is far less understood. Methods We investigate whether resource allocation between egg size and clutch size is influenced by the ambient temperature and whether it may be related to apparent nest survival rate. We measured 1548 eggs from 541 nests of two closely related shorebird species, the Kentish Plover (Charadrius alexandrinus) and the White-faced Plover (C. dealbatus) in China, in four populations that exhibit contrasting ambient environments. We weighed females, monitored nest survival, and calculated the variance of ambient temperature. Results Although we found that egg size and clutch size were all different between the four breeding populations, the reproductive investment (i.e. total clutch volume) was similar between populations. We also found that populations with a high survival rate had relatively larger eggs and a smaller clutch than populations with a low nest survival rate. The latter result is in line with a conservative/diversified bet-hedging strategy. Conclusions Our findings suggest that plovers may increasing fitness by investing fewer, larger or many, small according local nest survival rate to make a similar investment in reproduction, and thereby may have an impact on population demography.

Abstract Background Vertebrates exhibit diverse sex determination systems and reptiles stand out by having highly variable sex determinations that include temperature-dependent and genotypic sex determination (TSD and GSD, respectively). Theory predicts that populations living in either highly variable or cold climatic conditions should evolve genotypic sex determination to buffer the populations from extreme sex ratios, yet these fundamental predictions have not been tested across a wide range of taxa. Results Here, we use phylogenetic analyses of 213 reptile species representing 38 families (TSD = 101 species, GSD = 112 species) and climatic data to compare breeding environments between reptiles with GSD versus TSD. We show that GSD and TSD are confronted with the same level of climatic fluctuation during breeding seasons. However, TSD reptiles are significantly associated with warmer climates. We found a strong selection on the breeding season length that minimises exposure to cold and fluctuating climate. Phylogenetic path analyses comparing competing evolutionary hypotheses support that transitions in sex determination systems influenced the ambient temperature at which the species reproduces and nests. In turn, this interaction affects other variables such as the duration of the breeding season and life-history traits. Conclusions Taken together, our results challenge long-standing hypotheses about the association between sex determination and climate variability. We also show that ambient temperature is important during breeding seasons and it helps explain the effects of sex determination systems on the geographic distribution of extant reptile species.

Developmental duration is a key life-history trait. Cooney et al. compile data on 3096 bird species to quantify the degree to which phylogenetic history, body size and ecological variables like predation risk or breeding phenology influence variation in developmental duration.

Adult survival is a key component of population dynamics, and understanding variation in and the drivers of adult survival rates and longevity is critical for ecological and evolutionary studies, as well as for conservation biology and practice. Tropical species of landbirds are often selected to have higher adult survival due to high nest predation rates, but it is unclear if the same patterns occur in other avian lineages with different life history strategies. Here, we investigate adult survival of three sympatrically breeding species of shorebirds in south‐west Madagascar: the endemic and endangered Madagascar plover Charadrius thoracicus and two more widely distributed African species: the white‐fronted plover C. marginatus and the Kittlitz's plover C. pecuarius. Using mark–recapture data from 1843 individuals breeding at an intensely monitored saltmarsh over a 13‐year period, we estimated annual rates of apparent survival (φ) corrected for encounter probability. Adult apparent survival rates were high for all three species (mean ± SE): Madagascar (φ = 0.899 ± 0.010) and white‐fronted plovers (φ = 0.923 ± 0.008). Kittlitz's plovers showed a difference between the first (φ1 = 0.719 ± 0.026) and subsequent transitions (φ2+ = 0.892 ± 0.014), suggesting that transient breeders are common in this species. For birds first captured as adults, these survival estimates translate to life expectancies of 9.72 (±1.11) years in Kittlitz's plovers, 9.36 (±0.98) years in Madagascar plovers and 12.48 (±1.32) in white‐fronted plovers. We hypothesise that a long lifespan could be an adaptation arising from the unique climatic pressures on the island of Madagascar that would otherwise lead to reduced fitness. However, long lifespans may not sufficiently compensate for a reduction in breeding opportunities due to possible climatic disruption in the future. Consequently, at least two of these plover species seem vulnerable to ongoing habitat destruction and changing climate cycles.

In a few species, males invest more than females in parental care while the females invest in mating competition and producing multiple broods for several mates. Species in the family Jacanidae are commonly used for studying this type of breeding system (called sex-role reversal), and previous studies found discrepancies and variation between species in the expected characteristics of reversed sex roles. Yet, a better understanding of sex role differences in breeding behavior in such species is crucial for disentangling possible evolutionary mechanisms leading to this peculiar breeding system. Sex-role reversal in the pheasant-tailed jacana Hydrophasianus chirurgus has been documented long time ago. Since the very early observation of this species, however, there was no attempt to provide a comprehensive and quantitative description of their breeding. This study aims to fill these knowledge gaps by investigating the sex role differences in the breeding behavior of pheasant-tailed jacanas, by observing and monitoring a breeding population in Taiwan. We focused on three main characteristics of sex-role reversal: (1) competition between females for access to males, such as agonistic and courtship behaviors, (2) polyandrous mating, and (3) male-only care. As expected, we found that females provide most of the territory defense toward conspecifics. Males also participated in agonistic behaviors, although less frequently than females. Furthermore, contrary to what was expected, we found that males spent more time than females on courtship behavior. Polyandrous females performed mating and laying sequentially with different mates but maintained the pair bonds simultaneously with multiple males. For the first time for the species, we could estimate that the average number of mates per female (i.e., degree of polyandry) was 2.4 and that at least 81.8% of the females in the population were polyandrous. Finally, our observations corroborated that brood care is predominantly provided by males, nevertheless females were also participating to some degree in brood attendance but never in direct care (i.e., brooding). This study highlights that some aspects of polyandrous breeding might deviate from stereotyped view on sex-role reversal, and stress the importance of further within species and comparative studies in order to fully understand the mechanisms leading to sex-role reversal.

Abstract Maturation (the age when organisms are physiologically capable of breeding) is one of the major life history traits that have pervasive implications for reproductive strategies, fitness, and population growth. Sex differences in maturation are common in nature, although the causes of such differences are not understood. Fisher and Lack proposed that delayed maturation in males is expected when males are under intense sexual selection, but their proposition has never been tested across a wide range of taxa. By using phylogenetic comparative analyses and the most comprehensive dataset to date, including 201 species from 59 avian families, we show that intense sexual selection on males (as indicated by polygamous mating and male‐skewed sexual size dimorphism) correlates with delayed maturation. We also show that the adult sex ratio (ASR), an indicator of the social environment, is associated with sex‐specific maturation because in species with a female‐skewed ASR, males experience later maturation. Phylogenetic path analyses suggest that adult sex ratio drives interspecific changes in the intensity of sexual selection which, in turn, influences maturation. These results are robust to alternative phylogenetic hypotheses and to potential life‐history confounds, and they provide the first comprehensive support of Fisher's and Lack's propositions. Importantly, our work suggests that both social environment and mate competition influence the evolution of a major life history trait, maturation.

Abstract Social monogamy has evolved multiple times and is particularly common in birds. However, it is not well understood why some species live in long‐lasting monogamous partnerships while others change mates between breeding attempts. Here, we investigate mate fidelity in a sequential polygamous shorebird, the snowy plover (Charadrius nivosus), a species in which both males and females may have several breeding attempts within a breeding season with the same or different mates. Using 6 years of data from a well‐monitored population in Bahía de Ceuta, Mexico, we investigated predictors and fitness implications of mate fidelity both within and between years. We show that in order to maximize reproductive success within a season, individuals divorce after successful nesting and re‐mate with the same partner after nest failure. Therefore, divorced plovers, counterintuitively, achieve higher reproductive success than individuals that retain their mate. We also show that different mating decisions between sexes predict different breeding dispersal patterns. Taken together, our findings imply that divorce is an adaptive strategy to improve reproductive success in a stochastic environment. Understanding mate fidelity is important for the evolution of monogamy and polygamy, and these mating behaviors have implications for reproductive success and population productivity.

Abstract Background Speciation with gene flow is an alternative to the nascence of new taxa in strict allopatric separation. Indeed, many taxa have parapatric distributions at present. It is often unclear if these are secondary contacts, e.g. caused by past glaciation cycles or the manifestation of speciation with gene flow, which hampers our understanding of how different forces drive diversification. Here we studied genetic, phenotypic and ecological aspects of divergence in a pair of incipient shorebird species, the Kentish (Charadrius alexandrinus) and the White-faced Plovers (C. dealbatus), shorebirds with parapatric breeding ranges along the Chinese coast. We assessed divergence based on molecular markers with different modes of inheritance and quantified phenotypic and ecological divergence in aspects of morphometric, dietary and climatic niches. Results Our integrative analyses revealed small to moderate levels of genetic and phenotypic distinctiveness with symmetric gene flow across the contact area at the Chinese coast. The two species diverged approximately half a million years ago in dynamic isolation with secondary contact occurring due to cycling sea level changes between the Eastern and Southern China Sea in the mid-late Pleistocene. We found evidence of character displacement and ecological niche differentiation between the two species, invoking the role of selection in facilitating divergence despite gene flow. Conclusion These findings imply that ecology can indeed counter gene flow through divergent selection and thus contributes to incipient speciation in these plovers. Furthermore, our study highlights the importance of using integrative datasets to reveal the evolutionary history and assist the inference of mechanisms of speciation.

Many know that one of the most important consequences of the First World War was the collapse of the Austro-Hungarian Monarchy. Yet only few know that the two defeated allies – Austria and Hungary – had not only lost large territories of their own to the neighbouring successors states, but they were also engaged in serious border dispute with each other between 1918 and 1921. This desperate struggle may seem as if it came out of nowhere since the three historic counties that composed the Western periphery of Hungary did not really suffered from deep political or social conflicts before the war, at least not on the surface and comparing to other multi-ethnic regions of Central and Eastern Europe. If we picture the old Habsburg Empire as a jigsaw puzzle then the Western Hungarian counties should be imagined as those oddly shaped interlocking and mosaiced pieces that geographically as well as culturally connected the two halves of the empire. Although the long but narrow area along the Western border of the Kingdom of Hungary was dominantly German-speaking for centuries, both countries were under Habsburg rule under which questioning the historical borders would have been simply unreasonable. This radically changed around the turn-of-the century when modern nationalism broke through in public life and became a main driving force behind political aspirations. The disintegration of historic Western Hungary and birth of Burgenland were a very complicated process in which regard the significance of nationalism and its radicalization in the Great War cannot be underestimated.

Abstract Background Sex-determining systems may profoundly influence the ecology, behaviour and demography of animals, yet these relationships are poorly understood. Here we investigate whether species with temperature-dependent (TSD) and genetic sex determination (GSD) differ in key demographic traits, using data from 181 species representing all major phylogenetic lineages of extant reptiles. Results We show that species with TSD exhibit significantly higher within-species variance in sex ratios than GSD species in three major life stages: birth or hatching, juvenility and adulthood. In contrast, sex differences in adult mortality rates do not differ between GSD and TSD species. However, TSD species exhibit significantly greater sex differences in maturation ages than GSD species. Conclusion These results support the recent theoretical model that evolution of TSD is facilitated by sex-specific fitness benefits of developmental temperatures due to bimaturism. Our findings suggest that different sex-determination systems are associated with different demographic characteristics that may influence population viability and social evolution.

Biases in adult sex ratio (ASR) are common, yet their causes and consequences are not well understood. Here, the authors analyse data from >6000 individuals of five shorebird species, showing that sex differences in juvenile survival drive ASR variation and biased ASR is associated with uniparental care.

Abstract Background Relatively little is known about the prevalence of blood parasites in shorebirds, especially those breeding in the tropics. The prevalence of blood parasites of the genera Plasmodium, Haemoproteus and Leucocytozoon was assessed in blood samples from Kentish plovers and cream-coloured coursers in Cape Verde, and samples of Kittlitz’s plovers, Madagascar plovers and white-fronted plovers in Madagascar. Results Only two of these samples were positive for Plasmodium: a Kittlitz’s plover was infected by a generalist lineage of Plasmodium that has already been reported in Europe and Africa, while in a white-fronted plover direct sequencing revealed a previously un-described Plasmodium lineage. Conclusion Potential explanations for the low prevalence of blood parasites include the scarcity of vectors in habitats used by these bird species and their resistance to parasitic infections.

Do islands harbour less diverse disease communities than mainland? The island biogeography theory predicts more diverse communities on mainland than on islands due to more niches, more diverse habitats and availability of greater range of hosts. We compared bacteria prevalences of Campylobacter, Chlamydia and Salmonella in cloacal samples of a small shorebird, the Kentish plover (Charadrius alexandrinus) between two island populations of Macaronesia and two mainland locations in the Iberian Peninsula. Bacteria were found in all populations but, contrary to the expectations, prevalences did not differ between islands and mainland. Females had higher prevalences than males for Salmonella and when three bacteria genera were pooled together. Bacteria infection was unrelated to bird's body condition but females from mainland were heavier than males and birds from mainland were heavier than those from islands. Abiotic variables consistent throughout breeding sites, like high salinity that is known to inhibit bacteria growth, could explain the lack of differences in the bacteria prevalence between areas. We argue about the possible drivers and implications of sex differences in bacteria prevalence in Kentish plovers.

Ground-nesting birds face many challenges to reproduce successfully, with nest predation being the main cause of reproductive failure. Visual predators such as corvids and egg-eating raptors, are among the most common causes of nest failure; thus, parental strategies that reduce the risk of visual nest predation should be favored by selection. To date, most research has focused on egg crypsis without considering adult crypsis, although in natural circumstances the eggs are covered by an incubating parent most of the time. Here we use a ground-nesting shorebird, the Kentish plover (Charadrius alexandrinus) as model species to experimentally test whether decoy parents influence nest predation. Using artificial nests with a male decoy, a female decoy or no decoy, we found that the presence of a decoy increased nest predation (N = 107 nests, p < 0.001). However, no difference was found in predation rates between nests with a male versus female decoy (p > 0.05). Additionally, we found that nests in densely vegetated habitats experienced higher survival compared to nests placed in sparsely vegetated habitats. Nest camera images, predator tracks and marks left on eggs identified the brown-necked raven (Corvus ruficollis) as the main visual nest predator. Our study suggests that the presence of incubating parents may enhance nest detectability to visual predators. However, parents may reduce the predation risk by placing a nest in sites where they are covered by vegetation. Our findings highlight the importance of nest site selection not only regarding egg crypsis but also considering incubating adult camouflage.

Understanding how incipient species are maintained with gene flow is a fundamental question in evolutionary biology. Whole genome sequencing of multiple individuals holds great potential to illustrate patterns of genomic differentiation as well as the associated evolutionary histories. Kentish (Charadrius alexandrinus) and the white-faced (C. dealbatus) plovers, which differ in their phenotype, ecology and behavior, are two incipient species and parapatrically distributed in East Asia. Previous studies show evidence of genetic diversification with gene flow between the two plovers. Under this scenario, it is of great importance to explore the patterns of divergence at the genomic level and to determine whether specific regions are involved in reproductive isolation and local adaptation. Here we present the first population genomic analysis of the two incipient species based on the de novo Kentish plover reference genome and resequenced populations. We show that the two plover lineages are distinct in both nuclear and mitochondrial genomes. Using model-based coalescence analysis, we found that population sizes of Kentish plover increased whereas white-faced plovers declined during the Last Glaciation Period. Moreover, the two plovers diverged allopatrically, with gene flow occurring after secondary contact. This has resulted in low levels of genome-wide differentiation, although we found evidence of a few highly differentiated genomic regions in both the autosomes and the Z-chromosome. This study illustrates that incipient shorebird species with gene flow after secondary contact can exhibit discrete divergence at specific genomic regions and provides basis to further exploration on the genetic basis of relevant phenotypic traits.

Parental care is among the most widespread and variable behavioral traits between and within species, associated often both with large fitness costs and benefits. Despite its fitness consequences and evolutionary significance, we know very little about the ontogeny of this behavior, specifically, whether and how social experiences from parents contribute to the development of parental care. Here we used a split-family experimental design to produce uniparentally raised zebra finch nestlings that were provisioned either only by their mother or their father from shortly after hatching until independence. We investigated whether zebra finch nestlings pay attention to who takes care of them (short-term social effects) and whether parental sex roles, i.e., how much each parent provides to offspring, are socially learned and how these early social experiences influence negotiation rules of parental effort as adults (long-term social effects). We found pronounced short-term effects: uniparentally raised young socialized more with their “caring” than with their “non-caring” parent in a two-way choice test and begged more for food from them. When paired as adults based on their caring parent, some combinations of these uniparentally raised finches did not coordinate normally during incubation as first-time parents. By nestling provisioning (and their second breeding) even these pairs assumed normal distribution of parental effort and we therefore conclude that early social experiences influence parental sex roles and coordination, but these can be overridden by own social experiences with the mate when starting to breed.

The bacteriophage lambda and its hostEscherichia coli provide a model system to study cell-fate decisions. Here, Trinh et al. develop a four-colour fluorescence system at the single-cell/single-virus/single-viral-DNA level and find phages cooperate during lysogenization and compete during lysis.

Environmental variation has been hypothesized to favour the evolution of large brains capable of adjusting behaviour to changing circumstances. Here, Sayolet al. find that across more than 1200 bird species, species with relatively large brains are indeed associated with more variable habitats.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

[This corrects the article DOI: 10.1371/journal.pbio.2000644.].

Genetically identical cells frequently display substantial heterogeneity in gene expression, cellular morphology and physiology. It has been suggested that by rapidly generating a subpopulation with novel phenotypic traits, phenotypic heterogeneity (or plasticity) accelerates the rate of adaptive evolution in populations facing extreme environmental challenges. This issue is important as cell-to-cell phenotypic heterogeneity may initiate key steps in microbial evolution of drug resistance and cancer progression. Here, we study how stochastic transitions between cellular states influence evolutionary adaptation to a stressful environment in yeast Saccharomyces cerevisiae. We developed inducible synthetic gene circuits that generate varying degrees of expression stochasticity of an antifungal resistance gene. We initiated laboratory evolutionary experiments with genotypes carrying different versions of the genetic circuit by exposing the corresponding populations to gradually increasing antifungal stress. Phenotypic heterogeneity altered the evolutionary dynamics by transforming the adaptive landscape that relates genotype to fitness. Specifically, it enhanced the adaptive value of beneficial mutations through synergism between cell-to-cell variability and genetic variation. Our work demonstrates that phenotypic heterogeneity is an evolving trait when populations face a chronic selection pressure. It shapes evolutionary trajectories at the genomic level and facilitates evolutionary rescue from a deteriorating environmental stress.

Similar to other yeasts, the human pathogen Candida glabrata ages when it undergoes asymmetric, finite cell divisions, which determines its replicative lifespan. We sought to investigate if and how aging changes resilience of C. glabrata populations in the host environment. Our data demonstrate that old C. glabrata are more resistant to hydrogen peroxide and neutrophil killing, whereas young cells adhere better to epithelial cell layers. Consequently, virulence of old compared to younger C. glabrata cells is enhanced in the Galleria mellonella infection model. Electron microscopy images of old C. glabrata cells indicate a marked increase in cell wall thickness. Comparison of transcriptomes of old and young C. glabrata cells reveals differential regulation of ergosterol and Hog pathway associated genes as well as adhesion proteins, and suggests that aging is accompanied by remodeling of the fungal cell wall. Biochemical analysis supports this conclusion as older cells exhibit a qualitatively different lipid composition, leading to the observed increased emergence of fluconazole resistance when grown in the presence of fluconazole selection pressure. Older C. glabrata cells accumulate during murine and human infection, which is statistically unlikely without very strong selection. Therefore, we tested the hypothesis that neutrophils constitute the predominant selection pressure in vivo. When we altered experimentally the selection pressure by antibody-mediated removal of neutrophils, we observed a significantly younger pathogen population in mice. Mathematical modeling confirmed that differential selection of older cells is sufficient to cause the observed demographic shift in the fungal population. Hence our data support the concept that pathogenesis is affected by the generational age distribution of the infecting C. glabrata population in a host. We conclude that replicative aging constitutes an emerging trait, which is selected by the host and may even play an unanticipated role in the transition from a commensal to a pathogen state.

Natural systems are, almost by definition, heterogeneous: this can be either a boon or an obstacle to be overcome, depending on the situation. Traditionally, when constructing mathematical models of these systems, heterogeneity has typically been ignored, despite its critical role. However, in recent years, stochastic computational methods have become commonplace in science. They are able to appropriately account for heterogeneity; indeed, they are based around the premise that systems inherently contain at least one source of heterogeneity (namely, intrinsic heterogeneity). In this mini-review, we give a brief introduction to theoretical modelling and simulation in systems biology and discuss the three different sources of heterogeneity in natural systems. Our main topic is an overview of stochastic simulation methods in systems biology. There are many different types of stochastic methods. We focus on one group that has become especially popular in systems biology, biochemistry, chemistry and physics. These discrete-state stochastic methods do not follow individuals over time; rather they track only total populations. They also assume that the volume of interest is spatially homogeneous. We give an overview of these methods, with a discussion of the advantages and disadvantages of each, and suggest when each is more appropriate to use. We also include references to software implementations of them, so that beginners can quickly start using stochastic methods for practical problems of interest.

Parental care plays a key role in ontogeny, life-history trade-offs, sexual selection and intra-familial conflict. Studies focusing on understanding causes and consequences of variation in parental effort need to quantify parental behaviour accurately. The applied methods are, however, diverse even for a given species and type of parental effort, and rarely validated for accuracy. Here we focus on variability of parental behaviour from a methodological perspective to investigate the effect of different samplings on various estimates of parental effort. We used nest box cameras in a captive breeding population of zebra finches, Taeniopygia guttata, a widely used model system of sexual selection, intra-familial dynamics and parental care. We investigated diurnal and reproductive stage-dependent variation in parental effort (including incubation, brooding, nest attendance and number of feedings) based on 12h and 3h continuous video-recordings taken at various reproductive stages. We then investigated whether shorter (1h) sampling periods provided comparable estimates of overall parental effort and division of labour to those of longer (3h) sampling periods. Our study confirmed female-biased division of labour during incubation, and showed that the difference between female and male effort diminishes with advancing reproductive stage. We found individually consistent parental behaviours within given days of incubation and nestling provisioning. Furthermore, parental behaviour was consistent over the different stages of incubation, however, only female brooding was consistent over nestling provisioning. Parental effort during incubation did not predict parental effort during nestling provisioning. Our analyses revealed that 1h sampling may be influenced heavily by stochastic and diurnal variation. We suggest using a single longer sampling period (3h) may provide a consistent and accurate estimate for overall parental effort during incubation in zebra finches. Due to the large within-individual variation, we suggest repeated longer sampling over the reproductive stage may be necessary for accurate estimates of parental effort post-hatching.

Adult body size is the result of important environmental, maternal and/or genetic effects acting on animals during development. Here we investigate how sexual size dimorphism (SSD) develops in seven species of Odonata: Anax imperator, Cordulegaster boltonii, Onychogomphus uncatus, Oxygastra curtisii (Anisoptera), Cercion lindeni, Ischnura graellsii and Platycnemis acutipennis (Zygoptera). SSD of both the last larval and adult stages of the same individuals, which were reared under laboratory conditions, was measured. The aims were to investigate (i) whether SSD develops during the larval stage, (ii) the direction of larval and adult SSD, and (iii) whether the direction of adult SSD can be predicted by the mating system of a given species (e.g. males of territorial species being larger than females and the opposite for non-territorial species). We found that although larval differences in size may be present between the sexes, these are not necessarily shown in the adult stage (they may change or disappear). Also, the mating system was not related to patterns of adult SSD. Differences in SSD in larvae may be caused by differential use of resources via differential niche-utilisation or sex-specific growth patterns. We highlight the fact that sexual selection favouring large male size and fecundity selection, which selects for large females may be acting on the observed patterns in SSD in adults.

Since we still know very little about stem cells in their natural environment, it is useful to explore their dynamics through modelling and simulation, as well as experimentally. Most models of stem cell systems are based on deterministic differential equations that ignore the natural heterogeneity of stem cell populations. This is not appropriate at the level of individual cells and niches, when randomness is more likely to affect dynamics. In this paper, we introduce a fast stochastic method for simulating a metapopulation of stem cell niche lineages, that is, many sub-populations that together form a heterogeneous metapopulation, over time. By selecting the common limiting timestep, our method ensures that the entire metapopulation is simulated synchronously. This is important, as it allows us to introduce interactions between separate niche lineages, which would otherwise be impossible. We expand our method to enable the coupling of many lineages into niche groups, where differentiated cells are pooled within each niche group. Using this method, we explore the dynamics of the haematopoietic system from a demand control system perspective. We find that coupling together niche lineages allows the organism to regulate blood cell numbers as closely as possible to the homeostatic optimum. Furthermore, coupled lineages respond better than uncoupled ones to random perturbations, here the loss of some myeloid cells. This could imply that it is advantageous for an organism to connect together its niche lineages into groups. Our results suggest that a potential fruitful empirical direction will be to understand how stem cell descendants communicate with the niche and how cancer may arise as a result of a failure of such communication.

Social behaviours are highly variable between species, populations and individuals. However, it is contentious whether behavioural variations are primarily moulded by the environment, caused by genetic differences, or a combination of both. Here we establish that biparental care, a complex social behaviour that involves rearing of young by both parents, differs between closely related populations, and then test two potential sources of variation in parental behaviour between populations: ambient environment and genetic differentiation. We use 2904 hours behavioural data from 10 geographically distinct Kentish (Charadrius alexandrinus) and snowy plover (C. nivosus) populations in America, Europe, the Middle East and North Africa to test these two sources of behavioural variation. We show that local ambient temperature has a significant influence on parental care: with extreme heat (above 40 °C) total incubation (i.e. % of time the male or female incubated the nest) increased, and female share (% female share of incubation) decreased. By contrast, neither genetic differences between populations, nor geographic distances predicted total incubation or female's share of incubation. These results suggest that the local environment has a stronger influence on a social behaviour than genetic differentiation, at least between populations of closely related species.

Understanding and resolving conflicts between phenotypic and genetic differentiation is central to evolutionary research. While phenotypically monomorphic species may exhibit deep genetic divergences, some morphologically distinct taxa lack notable genetic differentiation. Here we conduct a molecular investigation of an enigmatic shorebird with a convoluted taxonomic history, the White-faced Plover (Charadrius alexandrinus dealbatus), widely regarded as a subspecies of the Kentish Plover (C. alexandrinus). Described as distinct in 1863, its name was consistently misapplied in subsequent decades until taxonomic clarification ensued in 2008. Using a recently proposed test of species delimitation, we reconfirm the phenotypic distinctness of dealbatus. We then compare three mitochondrial and seven nuclear DNA markers among 278 samples of dealbatus and alexandrinus from across their breeding range and four other closely related plovers. We fail to find any population genetic differentiation between dealbatus and alexandrinus, whereas the other species are deeply diverged at the study loci. Kentish Plovers join a small but growing list of species for which low levels of genetic differentiation are accompanied by the presence of strong phenotypic divergence, suggesting that diagnostic phenotypic characters may be encoded by few genes that are difficult to detect. Alternatively, gene expression differences may be crucial in producing different phenotypes whereas neutral differentiation may be lagging behind.

Despite important recent progress in our understanding of brain evolution, controversy remains regarding the evolutionary forces that have driven its enormous diversification in size. Here, we report that in passerine birds, migratory species tend to have brains that are substantially smaller (relative to body size) than those of resident species, confirming and generalizing previous studies. Phylogenetic reconstructions based on Bayesian Markov chain methods suggest an evolutionary scenario in which some large brained tropical passerines that invaded more seasonal regions evolved migratory behavior and migration itself selected for smaller brain size. Selection for smaller brains in migratory birds may arise from the energetic and developmental costs associated with a highly mobile life cycle, a possibility that is supported by a path analysis. Nevertheless, an important fraction (over 68%) of the correlation between brain mass and migratory distance comes from a direct effect of migration on brain size, perhaps reflecting costs associated with cognitive functions that have become less necessary in migratory species. Overall, our results highlight the importance of retrospective analyses in identifying selective pressures that have shaped brain evolution, and indicate that when it comes to the brain, larger is not always better.